Apple supplier Foxconn Technology said on Saturday it had raised wages for its assembly line workers in China by 16 to 25 percent, as the company faces public scrutiny for its working conditions at its factories.

A prominent activist group however said the wages at Foxconn are still too low.

For workers in Shenzhen, a major manufacturing base for Foxconn, the increase raises monthly salaries to between 2200 yuan (US$350) and 2500 yuan. Previously, monthly salaries for Foxconn’s Shenzhen workers were at 1800 yuan.

Foxconn, which implemented the wage hike on Feb. 1, noted that its worker salaries had already exceeded the Shenzhen government’s mandated minimum monthly wage requirement of 1500 yuan. 75 percent of Foxconn’s assembly line workforce in Shenzhen are currently receiving wages of more than 2200 yuan, the company added.

Foxconn announced the wage increases as the company’s factories in China undergo an investigation by the Fair Labor Association (FLA), a labor rights group. Apple joined the FLA last month, and asked the group to audit its largest suppliers.

Despite Foxconn’s wage increase announcement, the employees monthly salaries are still too low, said Debby Chan, a project officer with Hong Kong-based labor watchdog group Students & Scholars Against Corporate Misbehavior. On top of their regular working hours, many of Foxconn’s employees will also do overtime work, adding an additional 60 hour to 80 hours to their work-month, she said.

Foxconn workers’ salaries also vary by location, Chan said. In the city of Zhengzhou, new Foxconn workers make an average monthly salary of 1,350 yuan, she said. “After the wage increase, it will be 1650 yuan,” she said. “I think Foxconn is playing with the numbers.”

Foxconn, one of the world’s largest electronic manufacturers, also supplies companies including Dell, Sony and Microsoft. But the company has faced repeated negative publicity for its alleged harsh working conditions.

In 2010, a string of suicides, involving employees jumping off buildings, prompted Apple to investigate. Last May, an explosion at a Foxconn factory in Chengdu, China, also led to three worker deaths, and more than a dozen other injured.

To comment on this article and other Macworld content, visit our Facebook page or our Twitter feed.